Sensor fusion for low power occupancy sensing
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Solution Overview
Problem
Current occupancy sensing systems in buildings face challenges in accurately detecting stationary occupants, distinguishing between humans and pets, and efficiently managing energy consumption, due to limitations in video-based systems, ultrasonic sensors, and passive infrared sensors.
Innovation Solution
A system combining color sensors to establish a background color map and time-of-flight sensors to determine height and velocity data, allowing for accurate occupant detection and discrimination between humans and pets, while minimizing energy consumption by using low-power sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video-based systems are used for occupancy detection, then occupancy detection capability is improved, but computational complexity and data processing overhead increase
Solution Approach 1:
The patent extracts and removes the computationally intensive video processing component from the occupancy detection system. Instead of using full video feeds, the system uses only depth data from time-of-flight sensors and color data from color sensors, eliminating the need for complex image recognition algorithms while maintaining occupancy detection capability.
Solution Approach 2:
The patent replaces the optical-mechanical video-based detection system with a sensor fusion approach using time-of-flight depth sensing and color sensing. This substitution eliminates the need for complex video processing hardware and software, reducing computational complexity while maintaining detection accuracy.
2Measurement precision
If video-based systems are used for occupancy detection, then occupancy detection capability is improved, but data processing overhead increases
Solution Approach 1:
The patent extracts only the essential data elements (depth and color) needed for occupancy detection, discarding the bulk of video data that would require processing. This extraction approach dramatically reduces data processing overhead and energy consumption while maintaining detection capability.
3Measurement precision
If ultrasonic sensors are used for occupancy detection, then motion detection capability is improved, but false positives increase
Solution Approach 1:
The patent merges ultrasonic motion detection with color sensor data and time-of-flight depth sensing. By combining multiple sensor modalities, the system can distinguish between actual occupants and false positive sources like moving air streams, significantly reducing false positive rates while maintaining motion detection capability.
4Use of energy by moving object
If PIR sensors are used for occupancy detection, then power consumption is reduced, but stationary occupant detection fails
Solution Approach 1:
The patent merges PIR sensor low-power operation with time-of-flight depth sensing and color sensing. The PIR sensor provides motion-triggered wake-up signals, while the time-of-flight and color sensors continuously monitor for stationary occupants, achieving both low power consumption and accurate stationary occupant detection.
5Use of energy by moving object
If color sensors are used for occupancy detection, then power consumption is reduced, but discrimination between humans and pets is lost
Solution Approach 1:
The patent merges color sensor data with time-of-flight depth data to enable discrimination between humans and pets. The combination of color information and height/depth measurements allows the system to distinguish human occupants from pets while maintaining the low power consumption characteristics of color sensors.
6Reliability
If PIR and ultrasonic sensors are combined for occupancy detection, then false positive events are reduced, but stationary occupant detection remains impossible
Solution Approach 1:
The patent merges PIR and ultrasonic sensor benefits (false positive reduction through multi-sensor validation) with time-of-flight depth sensing capability (stationary occupant detection). The time-of-flight sensor provides continuous monitoring for stationary occupants while the PIR and ultrasonic sensors validate motion-based detections, achieving both goals simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively detects and tracks occupants, reducing false positives and negatives, and optimizing energy use in smart building systems by accurately controlling lighting and HVAC systems.
Implementation Method 1
at least one second sensor configured to determine height data of the at least one occupant
Implementation Method 2
color sensors can detect the time dependent changes in reflected light SPDs caused by occupant presence
Data Source
AI summary
A system for detecting occupants in a room is provided. The system includes at least one first sensor configured to establish a background color map of the room in an unoccupied state and to detect color shift data resulting from at least one occupant entering the room, at least one second sensor configured to determine height data of the at least one occupant, and a controller configured to receive the color shift data and the height data and to generate equipment-control signals to operate at least one occupant-centric system.